The present invention relates to a method of and a system for determining a position of a ball relative to a playing field during a game involving repetitive volleying back and forth, such as tennis, volleyball or soccer.
Methods and systems of the above mentioned general type are known in the art. Optical and contact type electrical devices have been used to determine a position of a ball on a playing field during a game. In accordance with known methods, photosensitive electric eyes are used on boundary lines, or electrical contacting tapes are arranged along the edges of the playing field. The disadvantages of the optical devices are that a plurality of the electric eyes must be installed. Furthermore, they can be interfered with when a player runds between the ball and the electric eye. The disadvantages of the contacting tapes are that they require additional digging and placement of the tapes below and/or at the surface and connecting them to alarm device. Another method uses magnetically sensitive devices under the playing field. These have the disadvantages of requiring modifications to the ball which substantially change their playing characteristics. Modifications to make a ball magnetically sensitive are much more extensive than modifications to make a ball radar sensitive, and being magnetically sensitive affects the way the ball plays.